Antistat and binder for glass fibers

ABSTRACT

A PROCESS FOR REDUCING THE STATIC CHARGE AND BINDING GLASS FIBERS IS DISCLOSED, WHEREIN THE GLASS FIBERS ARE CONTACTED WITH A COMPOSITION COMPRISING AN ALKYLENE POLYOL, SUCH AS AN ALKYLENE GLYCOL, A LOWER ALKANOL, A POLYBASIC ACID, AND A SILICONATE COMPOUND. THE COMPOSITION IS APPLIED TO SILICEOUS FIBRES, ESPECIALLY GLASS FIBRES, IN EITHER LOOSE OR BLANKET FORM, TO REDUCE THE STATIC CHARGE THEREON AND TO FUNTION AS A BINDER FOR THE FIBERS. GLASS FIBERS TREATED BY THE COMPOSITION OF THE PRESENT INVENTION ARE USEFUL IN VARIOUS APPLICATIONS SUCH AS FOR BLOWN INSULATION.

3,827,900 ANTISTAT AND BINDER FOR GLASS FIBERS A. Carey Williams, P.0.Box 16347, Bel Air Station, Mobile, Ala. 36616 No Drawing. Filed July31, 1972, Ser. No. 276,314 Int. Cl. (109k 3/16 U.S. Cl. 106287 S 11Claims ABSTRACT OF THE DISCLOSURE A process for reducing the staticcharge and binding glass fibers is disclosed, wherein the glass fibersare contacted with a composition comprising an alkylene polyol, such asan alkylene glycol, a lower alkanol, a polybasic acid, and a siliconatecompound. The composition is applied to silicious fibers, especiallyglass fibers, in either loose or blanket form, to reduce the staticcharge thereon and to function as a binder for the fibers. Glass fiberstreated by the composition of the present invention are useful invarious applications such as for blown insulation.

BACKGROUND OF THE INVENTION The prior art has used many differentcompositions as binders for glass fibers, with most such binders beingpolyester resins, producing fiberglass compositions. Typical polyesterresins include linear polymers of a dibasic acid and a diol.

The Wismer et al. U.S. Pat. No. 2,999,834 discloses a process wherein acatalyst-containing coating is applied to glass fibers, which glassfibers can then be used as a reinforcing material in aninterpolymerizable material matrix. The catalyst-containing coatingcomprises a catalyst for the matrix material contained in a coatingvehicle, with the coating vehicle being typically a diester or adicarboxylic acid and a monohydric alcohol, such as, e.g. terephthalicacid and ethanol, or a linear polyester of such acid and a glycol, suchas ethylene glycol. The glass fiber coating of Wismer functions merelyas a catalyst-carrying material, and to some extent, as a couplingmaterial, and is not used as a binder per se.

The Varlet U.S. Pat. No. 3,271,182 discloses a process for producingmechanically shapable reinforced polyester resin sheets, with thereinforcing agent being, e.g. glass fibers. The glass fibers are firstimpregnated with a polyvalent metal salt in a diluent which is apolyhydric alcohol or a vinyl monomer, then the glass fibers areimpregnated with a mixture of an interpolymerizable thermosettingpolyester and a catalyst therefor. The polyesters may be made of maleicacid, or the like, and ethylene glycol, or the like.

Marzocchi et al., 3,287,096 discloses the use of amylopectin as alubricant for glass fibers, used in connection with a plasticizer whichmay be a polyalkalene glycol, a fatty ester of glycols, or an ester ofcitric acid.

SUMMARY OF THE INVENTION The present invention is directed to acomposition and process for functioning as an antistatic agent and abinder for silicious fibers, especially glass fibers, and mostpreferably for blown glass fibers which are used for thermal insulation.The composition which is applied to the glass fibers, preferably appliedat the point wherein glass fibers are entrained in air stream, comprisesa 4-component system including:

(a) An alkylene polyol, preferably a lower alkylene glycol, such asethylene glycol, propylene glycerol, and the like, or a poly (loweralkylene glycol).

(b) A lower alkanol, preferably a lower alkanol containing 14 carbonatoms, such as methanol, propanol, butanol, and most preferably ethanoi.

States Patent (C) A polybasic water soluble acid, preferably a polyducethe surface tension of pure distilled water by at least 50%, when usedin an amount of .04 weight percent therein, such as, for instance,methyl sodium siliconate (sold commercially under the trade name DowCorning 772).

DESCRIPTION OF THE INVENTION The present invention is directed to anantistat and binder for silicious fibers, especially glass fibers. Whenapplied to silicious fibers, the composition of the present inventionreduces or dissipates the static electrical charge thereof, and servesas a binder for the fibers. i

The composition comprises four essential ingredients, as follows:

(a) An alkylene polyol, preferably an lower alkylene glycol or poly(lower alkylene glycol), such as ethylene glycol, propylene glycol,glycerol, polyethylene glycol of molecular weight up to 600, and thelike.

(b) A lower alkanol, preferably a lower alkanol containing 1-4 carbonatoms, such as methanol, propanol, butanol, and most preferably ethanol,

(c) A polybasic water soluble acid, preferably a polybasic water solubleacid having 2 or 3 acidic groups per molecule and a molecular weight ofless than 250, such as maleic acid, tartaric acid, adipic acid, succinicacid and the like, especially citricacid.

(d) A water-soluble siliconate which reduces the surface tension ofwater, especially those siliconates which reduce the surface tension ofpure distilled water by at least 50%, when used in an amount of .04weight percent therein, such as, for instance, methyl sodium siliconate.

In addition to the above components, it will be readily appreciated bythose in the art that additional ingredients may be included in thecomposition of the present invention, without departing from the spiritthereof. For instance, a coupling agent may be added to the composition,or may be present upon the silicious fiber surface when the fibers arecontacted by the composition of the present invention, to improve theadhesion of the composition of the present invention, to such fibers.When applied to glass fibers used in the blown insulation field, thecoupling agents may assist in producing improved fire retardant orfireproofing results, and may allow improved control of the resultantinsulation density.

The preferred coupling agent is a silane coupling agent sold under thetrade name Dow Corning Z-6031 Silane which is a catonic, methacrylatefunctional silane coupling agent having the typical physical properties:

Percent Solids 50%.

Color Amber Brown.

Refractive Index a 25 C 1.457.

Specific Gravity a 25 C 1.06.

Viscosity a 25 C cs.

Flash Point, open cup 'F.

Solvents Mostly diacetone alcohol.

Suitable diluents Alcohols, Water.

Typical other'known coupling agents including the vinyl silane couplingagents, such as, for instance, vinyltriethoxy silane, vinyl trichlorosilane, vinyl triethoxy silane, vinyl triacetoxy silane and the like, aswell as "yaminopropyl triethoxy silane, and 'y-methacryloxypropyltrimethoxy silane. Other conventional additives for glass fiberreinforced resins may be added, if desired, such as ultravioletstabilizers, interpolymerization catalysts, and the like. It will beappreciated, of course, that the silicious fibers, including glassfibers, may contain conventional sizes thereon.

A significant advantage of the present invention resides in the factthat atmospheric pollution by skin and membrane irritants and suspendedglass fibers and glass fiber dust is greatly reduced, or eveneliminated. For instance, in the insulation of buildings with blownglass fibers, prior art systems involve a substantial respiratoryproblem with floating glass fibers and glass fiber dust. Also, most ofthe prior art antistat and binder compositons involved the use ofcomponents which were irritating to lung tissues, skin, eye and nosemembranes, and the like. Thus, the compositions of the present inventionand particularly the preferred embodiment involving ethylene glycol,citric acid, and ethanol, in addition to the siliconate, greatly reduceenvironmental pollution when used as a binder and antistat agent forglass fibers in the blown insulation field.

In the installation of blown insulation, it is conventional to passfibrous glass rovings through a so-called chopping device and thenentrain the chopped fibrous glass in an air stream which deliverschopped fibrous glass to the desired points of application. Variousadditives may be added to the air stream, either before or after theentrainment of the chopped fibrous glass. In an especially preferredembodiment of the present invention, the antistat and binder compositionof the present invention is added to the air stream, either just priorto the point where the air stream entrains the chopped fibrous glass, orjust after such entrainment. It will be appreciated, however, that theantistat and binder composition can be added to the entrained choppedfibrous glass stream after discharge from the entrainment apparatus, butthis is not preferred. It may be desirable in some instances to add oneor more components of the present invention at a point in the entrainingair stream ditferent than the points wherein other additives are added.It is preferred that the composition contain at least one silanecoupling agent, as described hereinabove, as the coating componentsappear to interact at a faster rate in the presence of such a silanecoupling agent.

The alkylene polyol is a substantially water-soluble polyol, preferablya lower alkylene polyol of 2-4 carbon atoms, most preferably containing2-3 hydroxyl groups, although it will be appreciated that more carbonatoms and/or a greater number of hydroxyl groups may be present in thealkylene polyol. Preferred lower alkylene polyols include propyleneglycol, glycerol, and, most prefrably, ethylene glycol. Poly loweralkylene glycols, such as polyethylene glycol and polypropylene glycol,can also be used. Mixtures of alkylene polyols may be used.

The lower alkanol is most preferably ethanol, as the properties of theresulting composition are most satisfactory when ethanol is used, andthe use of ethanol eliminates health hazards associated with most otherlower alkanols. It will be appreciated, however, that alkanols of 1-4carbon atoms, such as methanol, propanol, isopropanol, and the like, maybe used to replace all or part of the ethanol, but precautions should betaken to insure that the fumes of these lower alkanols are not inhaledby Workers. If a denaturant is present in the ethanol, it should bechecked to insure that it does not interfere with the reaction of theethanol with the other components of the composition of the presentinvention. Mixtures of lower alkanols may be used.

The polybasic acid is preferably citric acid, as most favorable resultshave been obtained with the use of citric acid. However, other polybasicacids may be used to replace all or part of the citric acid, includingpolybasic water soluble acids, preferably polybasic water soluble acidshaving 2 or 3 acidic groups per molecule and a molecular weight of lessthan 250, such as maleic acid, tartaric acid, succinic acid, and thelike. It is essential that the polybasic acid, like the other componentsof the present composition, be substantially water soluble (i.e. solubleat least to the extent of 3% by weight in pure distilled Water at roomtemperature.) Mixtures of polybasic acids may be used.

The fourth component of the present invention is at least one watersoluble siliconate which reduces the surface tension of water. Asmentioned hereinabove, the siliconate should reduce the surface tensionof pure distilled water by at least 50%, when present in an amount of0.4% by weight. The preferred siliconate is methyl sodium silconate,sold under the trade name Dow Corning 772.

The order of addition of the components of the coating composition ofthe present invention is extremely important, and, in fact, critical.The alkylene polyol and the lower alkanol are first mixed together andthen the polybasic acid is added to such mixture. While the sodiumsiliconate can be added prior to the addition of the polybasic acid,this approach is definitely not preferred for lower temperatureapplication, e.g., 60 F., as greatly improved results are obtained ifthe water soluble siliconate is added after the polybasic acid has beenadded to the mixture of alkylene polyol and lower alkanol. However, forhigher temperature applications, e.g., F. applications, it is preferredto add the siliconate prior to the acid. While the silane coupling agentmay be added at any point in the production of the antistat and bindercomposition, as long as adequate care is taken to insure that thecoupling agent is not precipitated, it is greatly preferred to add thesilane coupling agent after the addition of the siliconate.

The composition of the present invention is applied in an aqueoussystem, and the water may be added to the composition at various pointsin the formation of same. However, it has been found greatly preferredto add the siliconate to the composition in the presence of at least 400weight percent of water, based on the weight of the siliconate.Likewise, it has been found greatly preferred to add the silane couplingagent in an aqueous system, wherein the weight ratio of waterzsilane isat least 20:1, preferably about :1, or greater.

The amount of water in the aqueous system may vary widely. It isgenerally best to use at least 30 percent by volume of the system ofwater, as lower amounts of water result in a system which is difficultto use in spray applications. If amounts of water in excess of 70percent or so by volume of the mixture are used, problems may beencountered in that insufiicient amounts of the active coatingcomponents may be applied, or else too much water must be removed inorder to readily produce a dried coating composition upon the siliciousfibers. For these reasons, the amount of water used is generally from 3070 percent by volume of the mixture, most preferably about 50 percent byvolume of the mixture.

In the preferred embodiment of producing the compositions of the presentinvention, the alkylene glycol and the lower alkanol are mixed together,the dibasic acid is added, and then an amount of water is added,corresponding to at least 30 percent by volume of the mixture,preferably about 50 percent by volume of the mixture. Thereafter, thesiliconate and the silane are added to this aqueous mixture, with theaqueous dilution of these ingredients set forth hereinabove.

The mixing of the ingredients described hereinabove is preferablyconducted at substantially room temperature, although higher and lowertemperatures may be used if desired, e.g., from 35 F. to about 100 F.,preferably between 45 and 75 F. The 4-component composition, optionallycontaining the silane coupling agent, is generally stable for at least12 hours. If the composition is to be stored for a greater time, thefinal step of mixing the siliconate (and the silane, if used) may beomitted, and the aqueous system of alkylene polyol, lower alkanol, andpolybasic acid is generally storage stable for several days underambient conditions if stored in an inert container.

It has generally been found that ferrous metal containers and polyvinylchloride containers are to be avoided, and polyethylene, aluminum,copper and bronze containers are satisfactory, with polyethylenepreferred for extended storage times.

The composition of the present invention will be applied to siliciousfibers in widely varying amounts. For instance, in the case of glassfibers, it is preferred to apply about 4 oz. of the composition of thepresent invention to 30 lbs. of fiber, at an application temperature of70- 80 F. Because of component volatilization, lower amounts of thecomposition may be used at lower temperatures, and vice versa. The useof composition of the present invention within the aforesaid rangeresults in a coating of substantial continuity on the silicious fibers,in the case of glass fibers of a type and diameter typical of the blowninsulation field. Of course, lower amounts of the composition of thepresent invention may be used to produce a discontinuous coating uponthe fibers. Broadly speaking, the composition will be applied to thefibers in an amount of about 1-10 02., or even higher, of the coatingcomposition per 30 lbs. of silicious fiber.

The ratio of the ingredients in the 4-component com position of thepresent invention may vary, according to the application temperature,humidity, and fiber composition and free fiber content. In the typicalSouthern application involving temperatures of 80 F., the compositionwill contain about 16 oz. per gallon of ethylene glycol, oz. per gallonof ethanol, 9 oz. per gallon of citric acid, 4.5 oz. per gallon ofmethyl sodium siliconate, and about 0.1% by weight of silane couplingagent. The aforesaid amounts may be varied if ingredients other thanthose specified above are used, although it is generally preferred touse substantially molar equivalent amounts, based on the amounts of thepreferred ingredients. If lower application temperatures are utilized,the amount of alkylene glycol will generally be raised, and the amountfor lower alkanol and polybasic acid will be lowered. For instance, forapplication at 60 F., about 18 oz. per gallon of ethylene glycol, about8 oz. per gallon of citric acid and about 8 oz. per gallon of ethanol,or equivalents thereof, will be used. Generally, the amounts ofsiliconate and silane, if the latter is used, are relatively independentof the application temperature.

Broadly speaking, however, the ingredients of the coating composition ofthe present invention will be used in the molar ratios set forth below:

lower alkanol 1 mole polybasic acid 0.151.0 moles alkylene polyol0.7-3.7 moles In addition to the above components of the presentinvention, the composition will preferably contain the weight ratios setforth below, based on 1 part by weight of ethanol:

citric acid 0.8-4 parts by weight ethylene glycol 1-5 parts by weightsodium methyl siliconate 0.1-1 parts by weight The above composition mayoptionally contain from 0.001, or less, percent by weight of silanecoupling agent, up to 5% by weight or so of silane coupling agent,although generally no substantial advantage will be noted using levelsof silane coupling agent greater than 0.5% by weight.

The amount of siliconate in the above formulation is quite critical, andeach composition within the aforesaid range should be checked to insurethat the siliconate is within the proper range, as too much siliconateresults in the production of a floury powder, or a granulation product,on the surface of the composition upon exposure to air. Preferably,therefore, the siliconate will be used in an amount of less than .7parts per part of lower alkanol.

The content of the citric acid or other polybasic acid is critical inthat amounts of acid in excess of the stoichiometric amount, based uponthe alkylene glycol and lower alkanol, taking into consideration, ofcourse, possible volatilization of these components and especiallyvolatilization of the lower alkanol, is liable to result in filamentbreakage, producing an undesirably high fuzz level. Therefore, in theabove coating composition ranges, it will be understood that thepolybasic acid will not be present in an amount substantially instoichiometric excess of the alkylene glycol and lower alkanol combined.

In addition to the application of the compositions of the presentinvention to insulating fibers, it will be readily appreciated that thecomposition of the present invention may be applied to loose siliciousfibers to bind such fibers into mats or boards for use in applicationwhich may or may not involve thermal insulation. In such applications,the fibers are generally contacted with the composition of the presentinvention on a production line, and it will generally be foundadvantageous to utilize a heating step to insure a rapid, full cure ofthe composition of the present invention. Generally, the heating stepwill involve a temperature of at least F., more preferably at least F.The heating temperature may be much greater than the aforesaidtemperatures, as long as the heating temperature is less than thedecomposition temperature of the components of the coating composition.Generally, however, the heating temperature will not involve atemperature above 400 F., although higher temperatures may be used, ifmuch shorter times of exposure are involved.

EXAMPLES OF THE INVENTION The invention will be understood more readilyby reference to the following examples; however, these examples areintended to illustrate the invention and are not to be construed tolimit the scope of the invention.

Example I The following materials were mixed at room temperature, in theorder indicated, to produce one gallon of coating composition.

First, 16 oz. of ethylene glycol and 10 oz. of ethanol were stirredtogether in a flask at room temperature. 9 oz. of concentrated citricacid were stirred into the mixture, and then distilled water was addedto amount to 50 volume percent of the resulting mixture. Thereafter, 4.2wt. percent of sodium methyl siliconate in an aqueous solution having awater-siliconate weight ratio of 4:1, was added to the above mixturewith stirring at room temperature. Next, 0.1 percent by weight of'y-methacryloxy-propyltrimethoxy silane in 100 parts of water was addedto the mixture at room temperature with stirring.

The resulting coating composition solution had a room temperature shelfstability of at least 24 hours.

The above described composition was applied to chopped glass fiberrovings in a Universal Insulating Volumatic Machine, with injection ofthe coating composition into the glass fiber-entrained air streamdownstream of the chopper. The coated glass fibers were directed intothe attic areas of a typical residential home, with no noticeablechemical odor and a minimum amount of dusting of glass fibers at 80 F.Within 24 hours, the coating composition had solidified into a firmadherent binder for the glass fibers, and no noticeable water contentwas noted thereon (a noticeable setting of the composition was notedimmediately after discharge from the machine nozzle).

From the above, it will be appreciated that this example resulted insubstantially no environmental pollution, wherein prior art efforts,using other antistatic and binder compositions generally result insubstantial health hazards from inhalation of the glass fibers into therespiratory system, as well as exposure of lung and skin surfaces andother body surfaces to irritants in the prior art coating composition.In addition, the prior art compositions generally involved substantialamounts of overspray, wherein the glass fibers adhered to attic walls,ceilings, and the like, so that the insulating effectiveness of a givenamount of applied glass fibers was greatly reduced.

The results obtained above suggested that other polyols may be used toreplace part or all of the ethylene glycol. For instance, it should bepossible to replace all or part of the ethylene glycol with an equalmolecular amount of one or more straight or branched chain alkane of upto 10 carbon atoms, having at least one hydroxyl group on each secondaryor tertiary carbon atom. Examples of such polyols are pentaerythritol,sorbitol, sucrose, and the like. The results obtained above also suggestthat polymeric polyols should be useful in the practice of the presentinvention, as replacement, in whole or in part, for the ethylene glycolor other alkylene polyol. Such polymeric polyols includepolysaccharides, such as dextrin, and polyvinyl alcohol or the like.

The above results also suggest that certain acids not substantiallysoluble in pure distilled water might be suitable for use in thepractice of the present invention it rendered soluble by the use of analkaline agent to raise the pH of the coating composition. For instance,prior to the addition of such acid, the aqueous solution of the polyoland the alcohol may be mixed with sodium hydroxide or even sodium methylsiliconate, which is quite alkaline, to a pH of at least about 8.0,preferably at least 8.5. This approach should allow less water-solubleacids, such as fumaric acid, to be utilized in the practice of thepresent invention. In following this approach, the use of the siliconateto raise the pH appears particularly preferred.

Example II Example I was repeated, except the siliconate and the silanewere added to the aqueous mixture of ethylene glycol and ethanol priorto the addition of the citric acid. This composition was somewhat moresuitable for use in applications involving higher ambient temperatures,i.e., 80 F., as less polymeric residue was found in the compositionstorage tanks of the application equipment.

I claim:

1. An antistat and binder composition for silicious fibers, saidcomposition comprising an aqueous system containing about 30 to about 70percent by weight of water, one part of at least 1 lower alkanol of 14carbon atoms, about 0.8-4 parts of at least 1 polybasic watersolubleacid having 2 or 3 acidic groups per molecule and a molecular weight ofless than about 250, about 1-5 parts by weight of a substantiallywater-soluble lower alkylene polyol or poly(lower alkylene glycol)wherein the alkylene groups contain 2-4 carbon atoms, and about 0.1- 1parts of at least 1 water-soluble siliconate which reduces the surfacetension of pure distilled water by at least 50% when used in an amountof 0.4 weight percent therein.

2. Composition as claimed in claim 1, additionally containing a couplingamounts of at least one silane coupling agent.

3. Composition as claimed in claim 2 wherein said coupling agent is avinyl silane.

4. Composition as claimed in claim 1, wherein said alkylene polyol isethylene glycol.

5. Composition as claimed in claim 4, wherein said low er alkanol isethanol.

6. Composition as claimed in claim 5, wherein polybasic water-solubleacid is citric acid.

7. Composition as claimed in claim 6, wherein said water-solublesiliconate is methyl sodium siliconate.

8. Composition as claimed in claim 7, wherein said methyl sodiumsiliconate is used in an amount of less than 0.7 parts.

9. Composition as claimed in claim 3, wherein said composition containsfrom 0.001 to 5 weight percent of said vinylsilane coupling agent.

10. Composition as claimed in claim 1, wherein from 0.15 to about 1.0moles of said polybasic acid and about 0.7 to about 3.7 moles of saidalkylene polyol are used per mole of lower alkanol.

11. Composition as claimed in claim 1, wherein said composition containsone part of ethanol, 0.8 to 4 parts of citric acid, 1 to 5 parts ofethylene glycol and 0.1 to 1 part of sodium methylsiliconate.

said

References Cited UNITED STATES PATENTS 2,393,863 1/1946 Myers 260Dig. 152,556,045 6/1951 Serdynsky et al. 260Dig. 15 2,990,307 6/1961 Stalego117-126 GS 3,287,096 11/1966 Marzochhi et al. l17126 GQ 3,405,00110/1968 Iler 1l7126 GQ 3,567,570 3/1971 Preston et al 117-126 GS ALLANLIEBERMAN, Primary Examiner U.S. Cl. X.R.

106-287 SE, 287 SB; l17126 GQ, 126 GS; 260Digest 15

